Sulphurized oils



Patented Apr. 12, 1938 UNITED STATES SULPHURIZED OILS aware No Drawing.Application December 23, 1936, Serial No. 117,901

4 Claims.

Our invention relates to sulphurized oils and more particularly tolubricants containing a specific class of sulphur containing compounds.This application is a continuation in part of our 5 copendingapplication, Serial No. 1l,588, filed March'18,1935.

In our copending application, we have disclosed an improved type ofsulphurized oil prepared by adding to a hydrocarbon oil a dihydric '10or monohydric ester of an unsaturated organic acid which ester has beensulphurized. In said application, the value of a 'sulphurized oil madein accordance with our application for use in cutting lubricants,extreme pressure lubricants and crank case lubricants was pointed out.Sulphurized oils made by adding sulphurized glycerides. or sulphurizedvegetable or animal oils to lubricants have long been known but theseoils do not possess the advantages of oils compounded by the use ofsulphurized dihydric and monohydric esters. The dvantage of oilscompounded with monohydric or dihydric esters arises from the fact thatno derivatives of glycerine are present, which derivatives will breakdown during use, liberating glycerine and therefore will cause gummingand sludging which is deleterious, especially in case of internalcombustion engines where high' temperatures and'pressures are involved,which will readily facilitate gumming and 30. sludging. v

' Lubricating oils prepared with monohydric and dihydric esters have thefurther advantage of being less viscous than those prepared bysulphurized glycerides. Moreover, the viscosity does not increase asrapidly on long time heating with sulphurized monohydric and dihydricester. This is very. important in commercial lubricants.

Higher speeds and greater bearing pressures in modern internalcombustion engines have made #9 it necessary for automotive engineers todevelop improved bearings. Modern bearings which have resulted from thisimprovement are of three general types, namely those comprising thecadmium alloys, those comprising the mixtures of copper and leadtogether with small amounts of other metals, and alloys containing ahigh perce'ntage of lead. While these new bearing materials are capableof withstanding higher pressures and greater speeds than the old Babbittbearings,- they are more susceptible to corrosion resulting from theaction of oxidation products of the lubri- One object of our inventionis to provide a sul- 'ssphurized lubricant which ,will inhibit corrosionwith respect to the new type of soft metal bearmgs.

Another object of our invention is to provide a lubricant containing asmall amount of sulphurized monohydricor dihydric esters, which 5lubricant will not be corrosive to bearing metals of the so-called softmetal alloy class but which will nevertheless be sufflcienty chemicallyactive to precipitate objectionable compounds of such metals assulphides.

Another object of our invention is to provide a lubricant possessing ahigh degree of oiliness.

Another object of our invention is to provide a lubricant which willpossess a decreased rate of oxidation. i

Another object of our invention is to provide a lubricant of decreasedsludging characteristics.

Other and further objects of our invention will appear from thefollowing description.

We have pointed out in our copending application, Serial No. 11,588 thatthe monohydric and dihydric esters of unsaturated fatty acids, whensulphurized, will yield products which may be added to hydrocarbon oilsto obtain improved lubricants. 2

We have discovered that certain of the monohydric and dihydric esters,when prepared in a certain manner, are superior corrosion inhibitors andare therefore especially desirable for use with" the new type soft"metal bearings. Certain of these compounds falling within the genericclass and prepared in accordance with our invention, have thefurtheradvantage that they are oxidation and sludging inhibitors.

We do not know the theory of the new eifects produced. We believe,however, that the corrosion inhibiting and antioxidation effects of vthese monohydric and dihydric esters, prepared in a certain manner, maybe explained. Most metals tend to act as catalysts increasing the 40rate of oxidation. For example, whena hydrocarbon oil is heated incontact with air in the presence of copper, a sludge comprisinghydrocarbon oxidation products will form much more rapidly than if theoil is heated to the same temperature in a glass container out ofcontact with copper. This oxidation increasing effect of metals is trueto various degrees for other metals, Soaps and oxides of such metals ascadmium and iron are catalysts in oxidation reactions for pe troleumderivatives and are used, for example,

in the preparation of fatty acids and other oxidatlon products fromhydrocarbonsYThe sulpuhurized esters of our invention are strongly polarcompounds and we believe they tend to form a protective layer overmetallic parts serving to insulate the metal from the main body of oil,thus inhibiting the catalytic effect of the metal toward oxidation. Webelieve, further, that traces 05; such metallic salts as do form, suchas iron. soaps, copper soaps, lead soaps and cadmium soaps, which resultfrom the reaction of the oxidized hydrocarbons with the metals, areprecipitated by the sulphur in our sulphuretted esters. The sulphidesare insoluble in. hydrocarbon oil and are much poorer oxidationcatalysts than the soaps and the metals themselves. By the formation ofsulphides and their precipitation, the catalytic efiect is decreased andthe oxidation is minimized.

-We have discovered that certain types of sulphurized esters aresuperior to others and that these could be most advantageously preparedin certain ways. This type consists of monoand dihyciric esters preparedfrom fatty oils in which the linolenic or similar two double-bondedfatty acid content ranges from 10 to 60% and in which the linolenic orsimilar three or more doubleboiided fatty acid is present in quantitiesless than 5 per cent.

The instant application relates more particularly to the monohydricalcohol esters and particularly the methyl esters of those fatty acids,the glycerides of which are normally present in corn oil. Thoseparticular fatty acids, when sul phurized, produce a very superiorcorrosion inhibitor having marked antioxidation and antisludgingproperties as well as the property of increasing oiliness.

The superiority of these monohydric or di hydric esters of corn oilfatty acids over other similar esters of other fatty acids is due inpart to the fact that, when prepared to contain more than one atom ofsulphur to the molecule (12 to 18 per cent sulphur), they givea solutionin refined mineral oil which does not become cloudy.

The other high sulphur content esters, when blended with mineral oil,develop a cloud on standing for a week or more. While this cloud has noharmful effect upon the oil, it detracts from its appearance andincreases sales resistance.

The inhibiting effect on corrosion of an oil comprising a hydrocarbonoil containing a sul-' .phurized monohydric or dihydric ester of cornoil fatty acids was made with the Underwood apparatus which wasdeveloped by the General Motors Research department. It consists of achamber in which the soft metal bearing inserts are positioned andsubjected to jets of oil under a pressure. of 10 pounds per square inch.The oil is held at 350 F. and the test is run for a five hourv period. 3quarts of oil are charged to the apparatus and circulated. The oilbecomes oxidized during the test by contact with the air which is freeto circulate in and about the ap-.

paratus. In order to speed up the corrosive eife'ct of the oil, asoluble lead soap (usually lead naphthenate) is added. In testing ourinhibitor, we used a highly refined hydrocarbon (J as the base and addedlead naphthenate to the extent of .05 of one per cent (calculated aslead oxide). The mineral oil containing the lead naphthenate occasioneda loss of 450 mg. on a copper lead alloy bearing insert and 1810 gramson a cadmium alloy bearing insert. The mineral oil containing the .05 ofone per cent of lead naphthenate was blended with .1 of one per cent ofsulphuretted methyl ester ofcorn oil acids containing 18 per cent ofsulphur. Testing this .insert was 10 mg.

blend, the loss on a copper lead insert was only 10 mg. and the lossupon a cadmium alloy or maize oil. These esters may be prepared in ly bystirring at any temperature below 390 F. and preferably be ween 360 and370 The sulphur compound should be refined by means of any suitablemethod which will re-' move free and unstably bound sulphur and alsoimprove its color. Among methods that are satisfactory is contacting thesulphur compound with activated clays or carbons at temperatures ofapproximately 300 F.

A sulphurized ester containing about 18 per cent of sulphur may be thusprepared, which will not darken copper when blended with oil and has apowerful inhibiting eifect upon corrosion as hereinbefore pointed out.

As little as 5 to 10 per cent of suphur may be incorporated in the esterin preparing our inhibitor. Less than 10 per cent however is notrecommended as the effectiveness of the inhibitor increases withincrease in sulphur con tent. More than 20 per cent of sulphur is notadvisable since the sulphurized esters 'will .be too dark and will tendto be insoluble in hydrocarbon oils- The quantity of-inhibitor to beused when blending with'a hydrocarbon oil depends largely upon thecharacteristics of the crude oil from which the lubricant is made andthe degree of refining as well as conditions of use. From .01 of one percent to 5 per cent by weight of sulphurized ester with respect to thehydrocarbon oil is usually sufiicient to accomplish the desired results.v

While we have described our sulphurized ester for addition to ahydrocarbon oil, it is to be understood that it may be employed with ahydrocarbon oil, thickened with a soap, that is, a grease or greaselikelubricant as well as lubricating oils, properly so-called.

It. will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsub-combinations; This is contemplated by and is within the scope of ourclaims. It is further obvious that various changes may be made indetails within the scope of our claims withinvention, what ganic acids.the glycerldes of which are normany present in corn oil.

4. A lubricant including in combination a major proportion ofhydrocarbon oil and a. minor proportion of a sulphurized monohydrlc ordihydrlc ester of fatty acids, the glycerides of which are normallypresent in corn oil, said ester containing from 10 to 20 per cent ofsulphur.

- BER-T H. LINCOLN.

WALDO L. BTEINER-

